X-ray beam reveals hidden photographs

Once believed to be lost forever, badly degraded daguerreotypes, taken as early as 1850 have been revealed using rapid-scanning micro-X-ray fluorescence to see past the deterioration and recover the early images. Researchers at the University of Western Ontario in Canada led by Madalena Kozachuk employed synchrotron X-rays and fluorescence imaging to analyse old 19th-century daguerreotype plates.

Daguerreotypes used iodine-sensitized silver-coated copper plates that were developed using heated mercury vapor. Over time, the original photos on these plates faded away due to years of tarnish on the surface. However, the mercury particles still remain and by using its special X-ray imaging in a scanning process that takes 8 hours per plate and required completing at Cornell University in Ithaca, New York, the researchers were able to identify where mercury is distributed on each plate, recovering the original photos even when no trace of them can be seen. Importantly, the detailed scans area non-invasive way to study the historic relics.

“When we were able to get such resolution of those images beneath the tarnish, it was shocking. We were all thrilled with the outcome,” said Madalena Kozachuk, author of the paper.  “We have many different opportunities to expand this work. Other methods of restoring daguerreotypes have had limited success. Sometimes trying to clean up the plates has done more damage than good.”

“From a historical perspective, having these images now viewable. . . opens a whole new area of discovery,” she said. “You can recover portions of history that either were unknown or were thought to be lost.”

Kozachuk and her team tested the method out on two plates from the National Gallery of Canada’s photography research unit.  The two portraits, of an unknown man and an unidentified woman, may date from as early as 1850, before Canada was even a country.

19th-century daguerreotypes with original photo hidden by tarnish (left) and the photo recovered with X-ray beams (right).

Madalena Kozachuk is currently a PhD candidate in the Department of Chemistry, The University of Western Ontario.  Madalena does research in synchrotron radiation in application to artefacts of cultural heritage, with a focus on daguerreotypes.

Sep 2014 – Sep 2019 The University of Western Ontario, Department of Chemistry London, Canada.  Position: PhD Candidate

Sep 2017 National Gallery of Canada, Canadian Photography Institute, Canada.  Position: Research Fellow

Recovery of Degraded-Beyond-Recognition 19 Century Daguerreotypes with Rapid High Dynamic Range Elemental X-ray Fluorescence Imaging of Mercury L Emission Article